Copy protection scheme that was used for Dungeon Master on Atari ST and Amiga

http://dmweb.free.fr/?q=node/210

by bigbugbag • 12 years ago

163 109 12 years ago

dmweb.free.fr

wpietri2• 12 years ago

Nice. If I were writing an emulator, I would naively write a virtual disk drive that always worked. It would never occur to me that some programs would depend on certain reads being inconsistent.

I do wonder, though, if anybody has studied the ROI of antipiracy schemes like this. The only time I bothered to pirate software like this was when I was a penniless kid. And it's clear from this that the crackers were willing to put in absurd amounts of effort to break encryption; if one's opponents aren't rational economic actors, I'd think it would be easy to spend far more on copy protection than would ever get paid back in additional sales.

bunderbunder• 12 years ago

I suspect (but cannot prove) that it was greater back then.

This was before the Internet was really a thing, so even after the copy protection was cracked pirating software was still a hassle. Pirate BBSes took some effort to discover, and often had download quota systems you'd have to play along with. Even after that, you couldn't download a file without tying up the phone line and if a local BBS didn't exist you'd need to pay long distance charges, both of which risked the wrath of your parents.

So the "dedicated attackers" needed to be somewhat more dedicated, and were therefore rather less common. You could get a lot further by just preventing casual floppy copying, which was sometimes sufficient to discourage friends copying a game instead of buying a copy for each of themselves.

By contrast, warez present essentially zero hassle nowadays. That dramatically alters the equation.

Umn55• 12 years ago

"By contrast, warez present essentially zero hassle nowadays."

It was always easy, it has only recently become harder as online only and F2P has come online. Diablo 3 is a case in point.

bussiere• 12 years ago

How to say that in english ...

I was very young at this area , but we exchanged a lot of pirated game in school when we was 10 :)

We even find way to copy password manual protection by copying the disk or tunning the photocopier for the password manual in red.

During the school recreationnal time we talked a lot about games and we exchanged games, there was always someones who had a cousin or an uncle.

Great time, i owe a lot to this time and games.

I buy it now as much as i can (gog , re edition etc ...)

I get the atari at this time , and a lot of my friends too. I remember that i may have buy only one game or two with my pocket money because the package and manual were awsome. At this time the box and manuals was what makes me buy games more than pirate then :)

beagle32• 12 years ago

By contrast, warez present essentially zero hassle nowadays.

And they come with free malware to top!

SixSigma2• 12 years ago

To paraphrase Tanenbaum

Never discount the bandwidth of an envelope full of floppy disks in the post.

SeanDav• 12 years ago

If all that time, effort and brainpower had rather gone into making it a better game, they likely would have done a whole lot better in terms of reach and ultimately, profit. However copy protection was the standard method in those days, so one can only speculate on what might have been.

waterlesscloud• 12 years ago

It's rated as one of the top (if not the top) games of its era. It was the all-time top seller on the Atari ST platform in question.

They did great with the resource allocations they chose to make.

shmerl15• 12 years ago

What was great about wasting any resources on copy protection instead of using them for something actually useful for users?

shmerl15• 12 years ago

Indeed. And some never learn, otherwise DRM would have been dead by now.

paulhauggis2• 12 years ago

I've heard this before, but I disagree with it.

I used to run my own application company and sold windows apps. I could directly correlate piracy with sales. If my latest version had a key generator+crack on the various torrent sites, my sales would go down by as much as 30%. This was mostly because the torrent sites can easily get good keywords on Google and even get results above my own. I essentially had to complete with myself.

It would also waste my time with customer service. A user would have a cracked version installed, get malware, and then expect me to come to the rescue (and of course blame my software for their poor choices). The nerve of some people!!

Large companies like Adobe and Microsoft can take the hit, small shops can't.

But, these days are over now. I created a SaaS out of all of my apps and now have more sales than ever (and guaranteed monthly income). I can see more companies doing this to combat the environment that piracy has created. It's why Stallman is getting so ornery about it lately.

mdaniel• 12 years ago

I can see more companies doing this to combat the environment that piracy has created. It's why Stallman is getting so ornery about it lately.

Just for clarity, I doubt very seriously that Mr. Stallman disagrees with SaaS because it combats piracy. It is my understanding that his disagreement comes from the lack of options that are available to the consumer of those services: the freedom to take your data elsewhere, the freedom to audit [and possibly modify] the source code and probably 50 others that I don't even know.

On a separate note, I cannot even fathom a user who would call customer support for a cracked version. The only plausible situation I can imagine is that their child installed the app, cracked it and the parent wasn't savvy or strict enough about knowing where the child got the program and just assumed it was legit and therefore subject to support.

kabdib5• 12 years ago

Nah. Probably took them a week or two. Getting ahead of piracy was (maybe still is) a big deal.

Making the game better -- if the game is already good -- is unlikely to pay off as much as reducing the amount of piracy in the first few weeks of a title's lifetime.

bigbugbag8• 12 years ago

I sincerely doubt it. Dungeon Master was the all time best-seller on atari and maybe also on amiga, It has spawned a whole genre of games and is still a reference and is played to this day 25+ years later. It gained a cult following among people who played it to the point that one published a fully reverse engineered code in early 2014: http://www.dungeon-master.com/forum/viewtopic.php?f=25&t=298...

userbinator• 12 years ago

In order to prevent disk copy, the games make use of "fuzzy bits", also known as "weak bits" or "flakey bits"

Reminds me of the "weak sector" protection used on CDs, of which there was much technical information written on a few years ago; sadly a lot of that has somehow disappeared, but I managed to find one explanation of that scheme:

http://web.archive.org/web/20090603002402/http://sirdavidguy...

(The explanation there is not completely correct - the problem with more 0s than 1s or vice-versa is DC bias, since the signal from the read head is AC-coupled; here is another article that might help to explain that better: http://ixbtlabs.com/articles2/magia-chisel/ )

rnhmjoj• 12 years ago

I have never heard of fuzzy bits. I have found this if someone else is interested in it. http://www.atari-forum.com/viewtopic.php?t=9012

andsmi22• 12 years ago

This was a fascinating read. Somewhere in the late 80s/early 90s I picked up a floppy with a guide to cracking at a local computer store. I was then able to crack a few games with help of turbo debugger and Norton disk editor (file editor?) -- I mostly remember looking for int 16 (ah 02?) and then replacing the next few lines with nop's or changing jni to jmp -- I knew little of what I was doing but it was a blast. I was aware of certain protection that read bad sectors on a disk but if you did an exact floppy copy you could usually copy bad sectors-- different than this article. I do remember spending a few days on my cousins copy of altered beast and being very confused by it. I think it decrypted the game from disk or u compressed from disk into me,Roy so I could see the code I wanted to change in the debugger but not on the disk. This may have led to a failed attempt at a TSR to alter the code during runtime. I thi I i e eventually gave up. I also remember finding bible verses in the caveman ugh-lympics dump I think. Fond memories.

andsmi22• 12 years ago

I think this or part of this is what was on that shareware disk I got at the computer fair http://www.textfiles.com/piracy/CRACKING/act-13.txt the Buckaroo Bonzai Cracking the IBM PC sounds real familiar.

bigbugbag8• 12 years ago

you may want to read "Technical Documentation - Detailed analysis of the Dungeon Master and Chaos Strikes Back for Atari ST Floppy Disks" too then http://dmweb.free.fr/?q=node/1429

note the PDF at the bottom of the page.

raintrees• 12 years ago

This brings back memories... I worked at a company that used special duplication devices. We assisted with duplication of the game Rogue, and secured it with the main trick of making one of the sectors on the 5 1/4 floppy (might have been sector 8 or maybe 2, I don't remember which track) only half sized, while keeping the sector's recorded stats set to normal sizing (in the FAT? Not sure).

During game load, the executable would get the PC drive to do some kind of absolute positioning to read the "hidden" half sector, which would exist on these specially created discs.

Any subsequent copies made on normal PCs and copying equipment would copy the half sector as a normal full sector, missing the hidden part.

I remember talk about "fuzzy bits" at the time, but I cannot recall if we used them, and whom for...

kabdib5• 12 years ago

I wrote some copy protection code for a couple of game cartridges (the idea was to prevent people from trivially copying them into RAM).

One cart protected itself with checksums, computed over time from interrupt code, that were the key to decrypt a piece of code that did the "am I running from RAM instead of ROM?" check. Took me two weeks to write (I had two weeks of hanging around waiting for play testing to finish).

The software pirate who lived in my apartment complex knew I worked at Atari, and we were chatting one day when I mentioned that I'd written that particular cartridge. He lit up. "Yeah, that was a hard one. Took us three days to crack."

Copy-protection can be useful, but it's definitely an asymmetric game.

smosher_• 12 years ago

it's definitely an asymmetric game.

This. The crackers have to deal with whatever measures were taken by the authors. On the other hand, the authors have to deal with all of the measures available to everyone interested in cracking it.

rando38262• 12 years ago

I'm sceptical that the person hacking your console lived in the same apartment complex.

gaius• 12 years ago

Games was a much smaller world back then, and pretty much everyone with a 8-bit system had tried their hand at both writing games and hacking other peoples. When you write assembly language yourself, and own a debugger, then everything is "open source".

kabdib5• 12 years ago

175 Calvert Drive in Cupertino. Kind of a dump in the early 80s, probably all condos now [checks . . . nope, still there. Yuck].

I think one of us noticed the other carrying some Atari equipment in the parking lot, and we started chatting. Sure, a bit unlikely, but this was Silly Valley. I think the guy worked for Lockheed and cracking software was a hobby.

I kind of had this fellow in mind when I wrote the protection code. I figured it wouldn't stand up very long, and in fact, three days was a moral victory as far as I was concerned. I think he had as much fun with the code as I did :-)

belorn• 12 years ago

I am curious, do you feel the time spent on copy protection was worth it given the result?

kabdib5• 12 years ago

Oh yes, definitely.

1. The game got great reviews, so quality did not suffer.

2. In the 1980s, distribution of cracked titles was mostly by modem (BBS) or warez disks, and thus a LOT slower than today. Cracks would take weeks or months to get wide distribution.

3. Atari was paying me $30K/year. Let's double that for total employee load. It took me two weeks to write the copy protection, so that's roughly $2500 cost to Atari.

4. I think Atari's profit on carts was about $25. So to break even we had to deter 100 people from pirating the game and just buy it instead. You can wiggle the profit numbers around if you like, but it doesn't change them appreciably -- it's just not that many buyers that we have to swing in order to pay for development.

It's impossible to get numbers, but the fact that the game wasn't trivially copyable by the kid down the street (it took an expert cracker 3 days), that cracks were hard to obtain (little inter-pirate communication, bad distribution systems), and that the title sold maybe a million copies makes it almost certain that the protection not only paid for itself, but did so many times over.

zamalek• 12 years ago

Reminds me of my run-in with Starforce 5 in my youth (when I couldn't afford games).

It measures how many sectors there are in the rings on the disk. This number was validated against a portion of your CD key. At the time only a specific line of Plextor drives were able to create physical replications (this still might be the case). The Starforce driver prevented use of drive emulation. Removing the protection from the game (cracking it) wasn't simple, they advertise C++ obfuscation and thus likely inlined the protection routine in multiple places.

Two years after its launch the specific game I wanted (Track Mania Sunrise) could still only be pirated if you owned a Plextor.

w0wbagger• 12 years ago

I remember back in the day I used to crack Commodore 64 software, and some of the best protection I remember was when code was written and executed to the RAM in the disk drive, using the intelligent 1541 drive to verify the original disk was in the drive. It was brilliant, and took me longer than any other program to crack. It required the used of a disk memory disassembler, really obscure stuff.

Sierra software used to use multiple encryptions of the original disk-verification code, if I remember correctly. I feel some residual guilt about it now, but I was 14, and honestly, I learned more 6502 assembler cracking code than I ever did writing it. It was like a puzzle. Sorry, Oil's Well developers.

qwerta2• 12 years ago

Some programs had embedded graphic subroutines executed when under debugger. It would set CRT frequencies too high and blow up the display.

shultays• 12 years ago

Sounds like a myth. No crt producer would allow such a case and even if it is true, I would expect lots of law suits.

to3m2• 12 years ago

It was a fairly common thing, I think? Modern CRTs can detect out of range inputs but at one point you just had to be careful not to supply out of range frequencies. No more onerous than putting the right fuel in your car...

tokenrove• 12 years ago

While this case might be a myth, there are plenty of documented "killer pokes": http://en.wikipedia.org/wiki/Killer_poke

AlyssaRowan5• 12 years ago

I'm not sure, but I never saw it as a trap payload.

Rather, it's something that could go wrong when overclocking, since the Xtals were often locked to the video sync rate (my Falcon's "Nemesis" was a real bugger for it); maybe it'd try to change into a mode that actually didn't have the clock it was expecting!

I don't know about "blowing up", but yes, if you put a bad signal into them, some of them might break. I had (probably still have, actually, somewhere, albeit modified for SCART with an LM1881 and my crappy soldering!) an Atari SC1224 RGB monitor in which you fed the horizontal and vertical sync frequencies separately (rather than composite - hence the LM1881 being needed to split the sync). And at one point I had a Falcon, with Nemesis, and Videlity. The monitor did NOT like it if you fed it a horizontal sync outside the 15.6-15.8KHz range (like, say, VGA's 31468.5Hz; oops!).

The result was the big transformer in the back (line output transformer?) heating up and whining and the caps building up voltage, the screen's black level warming to an alarming dull green… I don't think I'd have wanted to keep the power on another few seconds! Although it'd probably only have burnt something out, I didn't want to break anything.

Point is, some CRTs are a bit more… direct than others. I hear the vector monitors (as used in Tempest) are particularly hairy beasts.

ddingus2• 12 years ago

There were failure modes they didn't always think about.

I once killed off an 80's era TV I was using for a display on a microcontroller. At the time, I was writing low level NTSC driver code, and was abusing the standard a little for some color advantages.

A combination of bright screens, overly dark ones ( sync in the visible raster), and misplaced vertical blank pulses popped that TV. It never displayed the same again.

Still worked, but was just crappy.

As monitors age, they can become vulnerable to this kind of thing. Not so much a single value, or poke, but ugly code intended to stress a display could take a few of the edge case ones out.

qwerta2• 12 years ago

I blow up 14 inch VGA display in Linux by setting wrong horizontal and vertical frequencies.

Kiro• 12 years ago

while most copy protections are defeated in a matter of hours or days by experimented hackers

I'm very amazed by this. How can this even be possible? Is there a standard formula that breaks every copy protection out there?

mootothemax4• 12 years ago

I'm very amazed by this. How can this even be possible? Is there a standard formula that breaks every copy protection out there?

For the most basic protection, find out where the copy protection check takes place, and patch the executable to skip over that check.

Obviously this would only work for the most trivial of copy protection. The basic principle remains the same, though.

stevekemp3• 12 years ago

Quite often these checks are just so simple and half-hearted that once you have even a little experience they're obvious.

A most basic protection, for example, might make the user enter a serial number to register a piece of software. If you enter the correct number then all is OK, if you enter the wrong number a message-box might appear saying "Sorry registration number is invalid".

Displaying that message-box almost immediately makes the cracking job 80% simpler. Disassemble the program, look for the reference to the text-string. Then look for a "compare + jump" that goes to that area of the code. 99% of the time the comparison will be "Is the serial number OK?" and if you remove the jump, or invert it ("jmpz -> jumpnz"), you're done.

If you want to read more you can find mirrors of +fravias documentation and demonstration site online which were live back in the day and introduce this stuff, and lots more:

http://71.6.196.237/fravia/academy.htm

ryanjshaw• 12 years ago

Almost all (?) protection ultimately requires some kind of feedback that you can work backwards from, so it was always a losing battle for developers. In a similar vein, I remember having the Grand Theft Auto 1 demo. Because it was an open world, it had a time limit on how long you could play the game.

The countdown was displayed in red digits in the corner of the screen. I used SoftICE to set a memory write breakpoint on the video framebuffer at the location where the timer was displayed. That allowed me to locate the code printing out the timer. That in turn gave me the address of the timer variable, against which I set another memory breakpoint, which brought me to the routine that was counting down the timer. A 1 byte patch effectively disabled the timer and allowed me to play for hours.

spiritplumber• 12 years ago

Wow. I made dinner for Fravia and crew once. Basically they just showed up at my place, and I was so honored that I raided the pantry.

klez• 12 years ago

That was how I cracked WinRAR back in the days.

Or better, I got rid of the annoying popup.

ddingus2• 12 years ago

An early favorite of mine was the disk check in Ultima II. Origin used a bad sector to verify original disk scheme.

Consumer drives could not make a bad sector, only firmware modified drives could, and I didn't have one at the time.

Based on some successful cracks I did on the Apple ][, I started working through the code, only to find out they didn't check for a specific error, just an error.

Upon seeing that, I restarted my Atari with the copied disk in the drive. Ataris made a beep for each sector loaded, which was very handy. About 19, or maybe it was 23 beeps later, I opened the drive door waited for the error, closed it, and the game worked just fine.

No need for a HEX patch.

wiz213• 12 years ago

I remember cracking Teenage Mutant Turtles and IBM Writing assistant just with the "debug" tool provided in the standard MS-DOS. It definitely took half an hour or so. The tests were very dumb, that's for sure. Just replacing a "JE" by "JNE" or something like that would do the trick.

I also cracked Ultima 6. That took me 3 days of intense work. The protection was hidden in the dialog engine. So you were not seeing the actual code, but the interpreter of dialogs actually interpreting the protection in the dialog engine (that was a super simple interpreter, more like a state machine). In the end, it was just a matter of understanding the dialog data and extracting the answer to the protection question ("on page 34, what is the third word ?").

I also cracked some football game by writing a program that would intercept disk access and the replay the disk-errors to cheat it. An emulation layer if you like.

The games that I've never cracked were Elite 2 frontier (the damn thing had checks all over the place and that was too hard); "le manoir de mortevielle" had super nasty decryption stuff. IIRC they were running decrypting code inside the interrupt table (so if you had to use the keyboard or timer to trace the code, then woosh :-)). I also went mad on Leisure Suit Larry were the protection was written in an interpreted language. At that time I was 16 or 17 and had no idea of what an interpreter was = >I've never understood the scheme :-(

You had also games with special messages in it such as "we worked very hard on this so don't crack us).

But the best thing I've seen is when I've tried to look into a already cracked game .the previous hacker Mr. Detergent I think, send a message along the line of "you're weaker than me". I Was sooooo upset :-)

I guess I cracked 20 or 30 games on PC. Most of them were very simple. But in the end things were getting harder. I had to use the Soft-ICE debugger (massive thing :-)) and then, well some had these hardware debugger and came the protected mode and, well, I got lost and started working on more creative stuff (Imphobia if one remembers :-))

stF

stevekemp3• 12 years ago

Having code run in interrupt routines reminds me of some of the hardest stuff I ever had to touch in the 8-bit days.

In the Z80 processor there is a magic register, the R-register, which has a value which increments magically after each instruction has executed. It is possible to calculate how much it goes up by, for example "XOR A" increments R by one, but "LD IX,23000" increments R by two.

If R is given a predetermined value at the start of the protection system, its value is known after every instruction until the loading system starts.

This was used in many of the protection routines on Spectrums, usually as part of code that would decrypt routines, and it was a pain for the same reason that the interrupt would have been - if you're in a debugger you mess up the global state of that register.

snarfy• 12 years ago

It always ends up as a boolean somewhere.

    /* complicated auth check */
    ...
    /* more complicated auth check */
    ...
    /* etc */

    if(!isValid) {
       /* do nasty things */
       ...
    }

You just need to find isValid and flip its value. Easy cheese in a good debugger.

I used to keep Soft-ICE installed on all my boxes. There were a few copy protected apps I didn't bother writing out the cracked file since I used them infrequently. Instead I'd set a breakpoint right before the e.g. isValid flag. Whenever I'd run those apps, Soft-ICE would pop up and I'd know I need to flip the bit for the full version.

Ecio78• 12 years ago

on the other hand sometimes protections are (were) lame. I remember probably 16-18 years ago "cracking" a CAD software worth thousands of dollars by just modifying the script used for the installer: the software was using a protection scheme based on some hard drive serial number, so that the activation code cannot be reused on a different system. The problem (for them) is that they implemented this in the installer too and the installer was using some kind of simil-VB scripting for doing the check. I modified it to print the activation code instead of just verifying it and pronto the installer became a keygenerator :D

It had been a great satifaction..

AlyssaRowan5• 12 years ago

Mm, it didn't take all that long to crack, when I did it for fun. My patched version of Mon had a reference search, and the code in the graphics.dat stuck out because I was single-stepping from interesting places. That trick makes deadlisting harder, but live debugging there's no real difference.

Side note: it kept the XBIOS/GEMDOS keyboard/mouse drivers in place, tried to unlink a debugger and wipe the RAM - but it forgot to patch out the good old Alt-Help "screen print" vector! So if you hide a routine in low memory, just above the vector tables, but below where it wiped, around $200-$400 ish from memory… <g> (Oh, and a Syncro Express would just duplicate the thing cold, even on Express mode, but that's no fun~!)

Chaos Strikes Back was bloody difficult as a game! Wonderful work, all around, it's a masterpiece. I bought more than one copy (and actually played Dungeon Master after CSB). I never did finish CSB!

On a similar thematic note, the later, futuristic first-person dungeon crawler Captive has much more interesting copy protection; the author (ratt) wrote his own disk routines (internally called RATTDOS). That was a tough one. It's very Amiga-ified inside, so I wouldn't be surprised if the Atari version shared most of the code. It has procedurally-generated levels, although I think it may be impossible to complete after a certain point.

The Atari ST version of Sid Meier's Civilization is also well worth checking out as a historian; it was written in C, and they left all the debugging symbols in! Fascinating; you can see the original "nuke-happy Gandhi" bug underflow first-hand, and the world maps were really just planar bitmaps, so when you'd figured out how they were stored, it wasn't hard to knock up an editor.

I also have fond memories of Wayne Smithson's Anarchy and its disk's Rob Northen exotic copy-protection's space-filling rant, although I suppose there are only a few people who even know what I mean about that. If you can find an original copy intact anywhere, break out a sector editor, and start reading. The format gets harder the further on in the disk you go. :)

To the person below who had trouble with Elite II: Frontier - um, perhaps your platform was harder? The executable we all seemed to have on the Atari was standalone, was one $4E75 RTS away from skipping the manual protection, and had absolutely no checksums in it at all (to my immense glee - I had lots of fun modding it)! I'm having some fun downtime playing its recently-released sequel Elite: Dangerous, too - but that's online, so of course I'm playing clean! (I did test a couple of cheats during the alpha, and reported to help the devs patch some of the most obvious gamebreakers.)

Other than online stuff, I honestly don't think they've discovered any particularly new tricks since those days. There's a lot of lost gems that get reinvented. The very best, newest, "anti-tamper" techniques are essentially, just bits of obfuscated code interleaved with checksums. Underwhelming, really. It boggles my mind that people still do that stuff - just make it easier to buy games, and it's hard to get easier than Steam! (My opinion of the "strong" obfuscation technique that bloats simple 32-condition IF statements to multi-gigabyte sizes is also pretty poor, as it stands at the moment, although the state-of-the-art could always improve.)

bigbugbag8• 12 years ago

Hey! thanks for this instructive comment.

I too had not managed to finish CSB at the time, but when it got ported to PC[1] with a feature to record your games, it spawned a speed run competition and I was shocked to learn that it can be defeated in less than 30 minutes, actually best time is 00h10m37s[2].

I gave it another try and manage to beat it after a few attempts, there's much trickery in how the dungeon is designed with falling traps on top of others and teleporters, but once you get your head your head around it and understand the diabolical demon director, it gets better.

Then there's the custom dungeons, and conflux is the real challenge, CSB is walk in the park in comparison.

[1] http://dmweb.free.fr/?q=node/851

[2] http://dmweb.free.fr/?q=node/856

AlyssaRowan5• 12 years ago

Agreed, it has a number of very interesting features in how it gets around limitations in its own engine!

And 10 minutes? Heavens above. Tell me that's tool-assisted.

mootothemax4• 12 years ago

God how I lived, breathed, loved and adored Captive! I think it's the only game I've ever truly fallen in love with.

I still can't face trying it in an emulator and having the spell potentially broken.

AlyssaRowan5• 12 years ago

I don't think that ruins it, really. It's also quite a loved game, although it hasn't been recreated like DM has. The lack of instructions was just criminal - there was a lot of the game that you had to learn by trial and error and you weren't given a lot of guidance!

The multi-way switches were a bit cheap, but the atmosphere and the little details were wonderful. The engine was very technically strong, too.

You should definitely check out Legend of Grimrock (and its Ishar-inspired sequel?) if you haven't already. I think they're on sale at the moment.

Speaking of Ishar, its copy-protection on the Atari deserved mention. Absolutely loaded with checksums, and it jams the reset vector, and it skews a protection track between two tracks and repeatedly changes tracks and reads at the same time to try to pick it up (which is what that strangled sound from the drive is!). I doubt that does your drive a lot of good, and it failed sometimes, which was… irritating.

j45• 12 years ago

Just an observations -- nice to see other Atari ST users in this thread -- it was a unique machine at a time where very little did what it could do at it's price point between gaming/computing/animation/music/desktop publishing/software development. It was quite a capable foe to the Mac at the time.

ekidd• 12 years ago

Another copy-protection classic was Spyro: Year of the Dragon: http://www.gamasutra.com/view/feature/131439/keeping_the_pir...

This used a multi-layered copy protection scheme. The first layers would show a dialog and quit. Later layers got progressively more vicious:

1. They'd remove 1 out of 10 gems needed to complete a certain level.

2. They'd randomly corrupt data.

3. They'd change the UI language at runtime.

Read the post-mortem I linked above; it's really fun. The basic idea was to require crackers to play the entire game very carefully, looking for subtle side effects that broke game play.

Ultimately, the protection was a success: It took almost 2 months to crack the game, resulting in a full Christmas season's worth of sales IIRC.

TillE• 12 years ago

a success: It took almost 2 months

This is all based on the idea that people who pirate games (or movies, etc) are also very impatient. I'm sure that's true for a certain percentage, but I don't know if it's that significant.

A current example is Dragon Age: Inquisition, which took a few extra weeks but still got cracked. But the game still has a ton of issues on PC (even for legitimate owners), so it's probably worth waiting another month or so for patches anyway.

asocial• 12 years ago

I think the 'success' was being able to delay the crack long enough for Christmas sales. Although whether the crack would have affected those sales considerably might be debatable.

cdr• 12 years ago

First week/month sales are critical to most media, as I understand it. Being a "best seller" can become a self-fulfilling prophecy.

Stymieing the impatient pirates is all you can hope to accomplish anyway.

TeMPOraL• 12 years ago

From the linked article:

Two months may not seem like a long time, but between 30 and 50 percent of most games' total sales occur in that time. Approximately 50 percent of the total sales of Spyro 2, up to December 2000, were in the first two months. Even games released in the middle of the year rather than the holiday season, such as Eidetic's Syphon Filter, make 30 percent of their total sales in the first two months.

deng• 12 years ago

I wonder: which software is the hardest to crack nowadays? As a hobby musician, I know that Ableton Live and Cubase seem to have excellent protection mechanisms, as this topic turns up regularly in forums. Especially Ableton seems to be nasty, as it is often usable for many hours before the protection kicks in. I think this is pretty clever, since it not only makes it harder for the cracker, but the user might be more inclined to buy the software after he has invested many hours in some music he cannot load anymore (Disclaimer: I own Ableton Live, and it is worth every penny.)

bigbugbag8• 12 years ago

bitwig is better imho, on the single point that it doesn't lock user to a specific OS.

zak_mc_kracken5• 12 years ago

Some of the most painful games I've had to crack were those that used obfuscated assembly (usually by xor'ing entire sections of code). This had the annoying effect of making it impossible to put breakpoints too far ahead of the code because assembly debuggers put breakpoints by modifying the opcodes (usually calling an interrupt) so by the time the unrolling routine comes along, it will decode the wrong bytes and you'll get garbage (and usually, a nice lock up or reboot).

The only way around that was to painfully go stage by stage, which was very time consuming.

ihenriksen• 12 years ago

Remember that from when I was a teen, the first crack took months after the initial release and came on like 20 disks, while the retail game was on 10 disks. Kevin R. Kachikian is the name on the patent, currently he is CTO at Amuse Inc. according to his LinkedIn page - must be a very smart guy.

Karunamon• 12 years ago

What do people use for drop-in debugging nowadays? SoftICE's original company went away a long time ago, and last I checked, the company that bought the code (and rebranded it something like Driver Studio) is also no more.

Copy protection scheme that was used for Dungeon Master on Atari ST and Amiga

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